Download FALL 2016 2 1 mV 2 1 mV − mgR − 1 t 5 4 3 2 + − = x x Fx

PHYS211–Exam3NAME__________________________
FALL2016
Thisexamhas20multiplechoicequestionsworth5pointseach.ForeachquestionchoosetheanswerthatisMOSTcorrect.
Markyouranswersonthisexamsheet&thescantron.Turninbothwhenyouarefinished.
1.Amassistiedtoastringoflength0.75-mandmovesinacircularpathontopofalevel(frictionless)tabletop.
Ifthemaximumtensionofthestringis20-N,whatwillbethemaximumkineticenergyofthemassbeforethe
stringbreaks?
a) 7.5J
d) 27J
b) 15J
e) Cannotbefoundwithoutmass&speedofthe
c) 20J
system
2.AspacestationhasacircularorbitaroundtheEarth.ThespeedofthesatelliteisV,theradiusoftheorbitisR.
Whatwillbetheworkdonebygravityduringonecompleteorbit?
c) mgR 1
a)
mV 2 2
d) − mgR b) −
1
mV 2 2
e) ZERO
3.Aparticleexperiencesavariableforcewhichproducesanaccelerationthatisproportionaltotime.Whatwill
betheresultingproportionalityforthekineticenergyoftheparticle?
a) t4
1
d)
b) t2
t2
c) t
e) Thereisnodependenceontime
Questions4-6refertothefollowinginformation:
Avariableforceof F( x ) = 3x 2 − 4 x + 5 Newtonsisappliedtoamassof5-kg.Themassstartsattheoriginand
displacestothepositionx=7meters.
4.Whatwillbethechangeinkineticenergyforthedisplacement?
a) ZERO
d) 620J
b) 124J
e) 1400J
c) 280J
5.Whatwillbethespeedofthemassafterthedisplacement?
a) ZERO
d) 38.0m/s
b) 10.6m/s
e) 56.0m/s
c) 24.8m/s
6.Whatistheaccelerationofthemassafterthedisplacement?
a) ZERO
d) 38.0m/s2
b) 10.6m/s2
e) 56.0m/s2
c) 24.8m/s2
7.TheweightofanobjectonMarsisone-thirdofthatonEarth.Whatwillbetheratioofkineticenergyofa
massMmovingwithspeedVonMarscomparedtothatofthesamemassmovingwiththesamespeedon
Earth?
a) 1:9
d) 3:1
b) 1:3
e) 9:1
c) 1:1
8.Whichofthefollowingbodieshasthelargestkineticenergy?
a) MassMandspeed4V
d) Mass4MandspeedV
b) Mass2Mandspeed3V
e) Allhavethesamekineticenergy
c) Mass3Mandspeed2V
9.WhichofthefollowingisNOTanexampleofenergyorwork?
a) ma 1
d)
mV 2 b) Pt 2
c) Fd 1 2
e)
kx 2
10.Abookslidesacrossarough,leveltabletop.Frictionwillchange:
a) KineticEnergyONLY
d) Kinetic&ThermalEnergyONLY
b) PotentialEnergyONLY
e) Kinetic&PotentialEnergyONLY
c) ThermalEnergyONLY
11.A20-kgcannonballisfiredatanunknownangleoverahorizontalfieldwithaninitialspeedof150m/s.When
itimpactsthegroundthespeedisonly145m/s.Whatisthechangeinthermalenergyforthesystem?
a) -100J
d) +14750J
b) +100J
e) ZERO
c) -14750J
Questions12&13refertothefollowinginformation:
Aforceof25-Nisrequiredtostretchandholdaspringadistanceof10-cmfromitsrestposition.
12.Amassof2kgisattachedtotheendofthespring.Thespringisreleased,whatwillbethespeedofthemass
whenitreachestheequilibriumpositionofthespring?
a) 1.12m/s
d) 2.5m/s
b) 1.25m/s
e) ZERO
c) 1.58m/s
13.Howmuchpotentialenergywillthespringhaveifitiscompressedtoadistanceof15-cmfromitsrest
position?
a) 2.50J
d) 5.63J
b) 2.81J
e) 37.5J
c) 3.75J
14.A1-kgmassslidesdownafrictionlesstrackfromanunknownheightand
throughaloop-the-loopasshowninthefigure.Whatminimumkinetic
energyisrequiredatthetopofthelooptopreventthemassfromfalling
offthetrack?
a) 5J
d) 49.05J
b) 12.26J
e) Cannotbecalculated
c) 24.52J
15.Anelevatormovesupwardwithaconstantvelocityof2m/s.Whichofthefollowingistrue?
a) Thekineticandpotentialenergiesbothincrease
b) Thekineticandpotentialenergiesbothdecrease
c) Bothremainconstant
d) Thekineticenergyremainsconstantbutthepotentialenergydoesnot
e) Thepotentialenergyremainsconstantbutthekineticenergydoesnot.
Questions16&17refertothefollowinginformation:
AcrateofmassMisshovedacrossalevelfloorwithaninitialspeedof3m/s.
Itcomestoahaltaftersliding2meters.
16.Whatisthecoefficientofkineticfrictionbetweenthecrateandthefloor?
a) 0.07
d) 0.67
b) 0.23
e) 1.50
c) 0.46
17.Ifhalfthemassisremovedfromthecrateanditisgiventhesameinitialspeed,howfarcomparedtothe
originaldisplacementwillthecrateslide?
a) Itwillslide¼oftheoriginaldisplacement
d) Itwillslidetwicetheoriginaldisplacement
b) Itwillslide½oftheoriginaldisplacement
e) Itwillslidefourtimestheoriginaldisplacement
c) Itwillslidethesamedisplacement
Questions18-20refertothefollowinginformation:
A75-kgskierslidesdownahillofheightH=50mandmakesajump
offofarampatanangleof30°withrespecttothehorizontal.The
skierreachesamaxheightofhduringthejump.
(Neglectfriction&airresistanceforthissystem)
18.Whatspeedwilltheskierhaveuponreachingtheramp?
a) 13.8m/s
d) 43.3m/s
b) 31.3m/s
e) 100m/s
c) 38.3m/s
19.Whatwillbethespeedoftheskieratthemaxheightofthejump?
a) ZERO
d) 33.2m/s
b) 12m/s
e) 37.5m/s
c) 27m/s
20.Whatisthemaxheightoftheskierduringthejump?
a) ZERO
d) 43.8m
b) 12.5m
e) 50m
c) 37.4m